Research Shows Heat Stroke Death Can Occur Even When Properly Hydrated

Prevention starts with recognizing one’s own limits.

Each year more than 1,000 people die from heat stroke in the United States. Long thought to be the product of dehydration, traditional prevention and treatment of heat related illness has been to drink more water. More recent research has proven that, while proper hydration is important, the key step to preventing heat stroke is to recognize when one is working too hard for the given environment and slowing down or stopping.

“One can absolutely suffer and even die from heat stroke even when properly hydrated,” said Dr. Brent Ruby, Director of the Center for Work Physiology and Exercise Metabolism at The University of Montana. “Prevention of heat stroke starts with recognizing our own limits while being active in hot environments. Our bodies are sending us signals to slow down and stop; we just have to know when to say when.”

The first stage of heat related illness is heat cramps with symptoms including painful muscle aches. The next stage is heat exhaustion with symptoms such as headache, nausea, dizziness, weakness, irritability, thirst and heavy sweating. Without taking steps to cool down, heat exhaustion can quickly progress to heat stroke when the body becomes overwhelmed by heat and is unable to regulate its core temperature. Symptoms of heat stroke include, sweating stops and the victim may become confused, lose consciousness, and have seizures. Heat stroke is a medical emergency that may result in death.

“In cases of HRI (heat related illness) that are developed during exertional heat stress, the individual is working too hard for the environment they are in and likely thinks — if I can stay hydrated, I will be fine,” explained Ruby. “But, that’s the wrong thinking. Even aggressive hydration strategies that attempt to match fluid loss one-to-one will not prevent the HRI. Knowing when to stop is the crucial step in prevention of heat stroke.”

Dr. Brent Ruby, Ph.D., FACSM is Director of the Montana Center for Work Physiology and Exercise Metabolism (Montana WPEM) at the University of Montana and a fellow of the American College of Sports Medicine (ACSM). Dr. Ruby’s research interests include nutritional strategies during ultra-endurance work/competition, muscle metabolism during and after exercise, the use of stable isotope tracers for the measure of water turnover and energy expenditure, and issues surrounding heat stress during arduous work. Differentiating WPEM from other labs, Ruby created a solar powered, mobile lab that allows controlled laboratory research to be meshed with raw field data to draw scientific conclusions.